Pressure sensing device

ABSTRACT

At least one pair of capacitively coupled electrodes contained in a structure is used to sense the deflection of a diaphragm in a pressure or force sensor for measuring the pressure or force exerted on the diaphragm. Preferably the structure has properties (such as one or more of the following: dimensions, hardness, area and flexibility) that are substantially the same as those of a real substrate, such as a semiconductor wafer or flat panel display panel.

CROSS-REFERENCE TO RELATED APPLICATION

This non-provisional application claims the benefit of provisionalapplications No. 60/828,000, filed Oct. 3, 2006, by Wayne G. Renken etal., entitled “Pressure Sensing Wafer,” and No. 60/828,351, filed Oct.5, 2006, by Wayne G. Renken et al., entitled “Pressure Sensing Wafer,”which applications are incorporated herein in their entireties by thisreference. This application is also related to an application Ser. No.11/392,220, filed Mar. 28, 2006, by Randall S. Mundt, entitled“Apparatus for Measurement of Paramenters in Process Equipment,” alsoincorporated herein in its entirety by this reference. This applicationis also related to an application filed on the same day as thisapplication, entitled “Shear Force Sensing Device,” by Wayne G. Renkenet al., also incorporated herein in its entirety by this reference.

BACKGROUND OF THE INVENTION

Semiconductor processing involves multiple steps to produce workingintegrated circuits on a semiconductor wafer. These steps may includedeposition and removal of various materials to form devices and to formthe electrical connections between devices. One process that removesmaterial from a wafer is Chemical Mechanical Polishing or Planarization(CMP). CMP generally leaves a planar surface, so that it is particularlysuitable for applications where an uneven topology might cause problems,for example where additional layers are to be deposited over a surfaceformed by previous processing. In particular, where multiple layers ofmetal interconnection are required in complex integrated circuits, CMPallows successive layers to be formed while maintaining a reasonablyflat surface for each successive layer.

CMP generally involves removing material from a wafer by a combinationof physical abrasion and chemical action. FIG. 1 shows a cross-sectionof a wafer 101 that is undergoing a CMP process. The wafer 101 ispressed down into a pad 103 by pressure applied to its upper surface.Pressure may be applied by a plate or pad. In some cases, pressure isapplied to the upper surface of the wafer 101 by hydraulic or pneumaticsystems. In this way the pressure may be controlled. In some cases,different pressure is provided at different locations on the uppersurface of the wafer. Here PE is provided near the edge, while Pc isprovided at the center. Different pressures may be provided for a seriesof concentric zones with separate hydraulic, pneumatic or other systemsto separately control pressure. Some relative movement is createdbetween the wafer 101 and the pad 103 by moving one or both of thesecomponents. As the wafer 101 moves with respect to the pad 103 its lowersurface is eroded. A retaining ring 105 keeps the wafer 101 in positionwith respect to structures providing pressure Pc and PE to the upperside of the wafer 101. A slurry 107 extends over the pad 103, includingthe area under the wafer 101. Slurry 107 may be introduced through holesin pad 103. This slurry 107 contains abrasive particles as well aschemical components that may react with material on the wafer. The pad103 is generally formed of a soft material that deforms under thepressure exerted by a wafer. In general, CMP systems operate so thatmaterial is removed from the lower surface of the wafer. Thus, a waferis generally turned so that the side of the wafer to be processed(generally, the side that contains semiconductor devices andconnections) is facing downwards.

In general it is desirable to remove material uniformly across thesurface of a wafer. Various parameters may vary across the wafer surfacecausing nonuniform removal rates. One parameter that may vary across thewafer is the pressure between the pad and the wafer. For example, inFIG. 1, pressure P1 may not be equal to pressure P2. It is generallydesirable to know the values of pressure P1 and P2 in order to adjustthe CMP process to obtain high uniformity. While the pressures P1 and P2between the wafer 101 and the pad 103 are affected by the pressures Pc,P_(E) applied to the top surface of the wafer 101, these relationshipsmay not be simple so that measuring Pc and P_(E) may not providesufficient information for process tuning. Therefore, it is generallydesirable to directly measure pressure at points across a wafer surfaceduring processing. CMP processes may also be applied to substrates otherthan semiconductor wafers, such as flat panel display panels andmagnetic heads or still other types of work pieces.

SUMMARY OF THE INVENTION

Before or periodically during the CMP process, the CMP head that is usedto apply pressure may also need to be tuned in a tuning process, so thatthe pressures that are applied to the substrates of the type mentionedabove are the desired pressures. Certain embodiments of the deviceproposed herein are also useful for the tuning process.

In one embodiment, a member comprises a diaphragm to which pressure isapplied, causing the diaphragm to deflect. At least one pair ofcapacitively coupled electrodes is used to sense the deflection of thediaphragm, wherein a capacitance of the at least one pair varies as afunction of deflection of the diaphragm. Thus, by sensing thecapacitance of the pair, it is possible to provide an indication of thedeflection of the diaphragm, which in turn provides an indication of thepressure on the diaphragm. Preferably, the member has a property that issubstantially the same as that of the substrate.

In general, removal of material in CMP is caused by two mechanisms:mechanical action and chemical action. Although these mechanisms areclosely linked, it may be desirable to try to separately measureparameters associated with each. One measurement that may be ofparticular value in measuring mechanical action is the frictional forcebetween a wafer and a pad as the wafer moves with respect to the pad.Generally, mechanical abrasion of material increases with increasingfrictional force. Frictional force may be used to provide a shear forcein a structure that deforms in a manner that indicates the magnitude ofthe shear force. In general, greater frictional force provides greatermechanical action in removing material during CMP.

In another embodiment, a member is used, which member is suitable forundergoing a CMP process to simulate behavior of said substrate in theprocess. At least one sensor is attached to the member. The at least onesensor measures a parameter related to a shear force on a surface of themember when such surface is in contact with and pressed against a CMPsurface and a lateral force is applied between the polishing orplanarization surface and the surface of the member. Preferably, thesurface of the member in contact with the CMP surface has a propertythat is substantially the same as a property of the surface of thesubstrate that the member simulates.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of a cross-section of a semiconductor wafer undergoinga CMP process useful for illustrating the invention.

FIG. 2 shows an example of a device or member such as one in the shapeof a plate having a cavity that is covered by a diaphragm for measuringpressure or force to illustrate one embodiment of the invention.

FIGS. 3A-3D are cross sectional views of capacitive pressure sensorsthat include a plate for measuring pressure or force to illustratedifferent embodiments of the invention. A cavity is formed in a base orcover portion of the plate or a separation layer between the base andthe cover.

FIG. 4A shows a plan view of a base formed from a bare Silicon wafer.

FIG. 4B shows a plan view of a cover formed from a thinned bare Siliconwafer. The cover is designed to be attached to the base of FIG. 4A toform an instrumented wafer that includes a number of capacitive pressuresensors for measuring pressure or force to illustrate one embodiment ofthe invention.

FIG. 5A shows a plan view of a base of a device according to anotherembodiment of the invention.

FIG. 5B shows a plan view of a cover designed to be attached to the baseof FIG. 5A to form an instrumented wafer.

FIG. 6A shows a first example of a wafer for measuring pressure or forcehaving sensor cavities with reservoirs illustrate one embodiment of theinvention.

FIG. 6B shows an alternative configuration to that of FIG. 6A.

FIG. 7 shows an example of a device with a reservoir system that has anopening 706 to the exterior of the device and a valve controlling theopening to illustrate one embodiment of the invention.

FIG. 8A shows an example of a device that includes a flex circuit formeasuring pressure or force.

FIG. 8B is a side view of a plate with a base and a cover enclosing acavity housing a pair of capacitively coupled electrodes not connectedto the cover to sense a parasitic capacitance in the plate to illustrateanother embodiment of the invention.

FIG. 8C is a top plan view of two pairs of capacitively coupledelectrodes adjacent to one another, one pair not connected to the coverto sense a parasitic capacitance in the plate, and the other pairconnected to the cover to sense a deflection of the cover.

FIG. 9 shows a device that includes a flex circuit and a plate having acavity that is covered by a diaphragm for measuring pressure or force,where the circuit is at least partially located in the cavity toillustrate another embodiment of the invention.

FIG. 10 shows another embodiment where a capacitive sensor is formedintegrally with a flex circuit.

FIG. 11 shows an example where a sensor cavity is formed within a base.Spacers are placed under a strain gauge so that the strain gauge candeflect downwards. A deflection augmenting element is placed between theupper surface of the strain gauge and the cover.

FIG. 12A shows an alternative arrangement where a strain gauge is bondedto a cover so that the strain gauge deflects along with the cover.

FIG. 12B shows an alternative embodiment to that of FIG. 12A.

FIG. 13 shows an embodiment where pressure sensors are placed between awafer and a CMP head.

FIG. 14 shows a pressure calibration apparatus that may be used tocalibrate a pressure sensing device.

FIG. 15 shows a CMP head and an attached wafer moving with respect to apad.

FIG. 16A shows a first rigid body in contact with a surface andconnected to a second rigid body by a portion of elastomeric material,where the FIG. 16A first rigid body at rest with respect to the surface.

FIG. 16B shows the first rigid body of FIG. 16A in motion with respectto the surface and is moved by applying a force through the second rigidbody. As a result of relative motion between first rigid body and thesurface, a frictional force F is created, acting as a shear forcecausing portion of elastomeric material to deform.

FIG. 17A shows a shear force sensor measuring deformation due to shearforce on an elastomeric material through changes in the electricalproperties of the elastomeric material as it is deformed.

FIG. 17B shows an alternative shear force sensor where resistance ismeasured between two electrodes connected by a structure that varies inresistance as a result of shear induced deformation. In particular, thestructure is arranged so that it elongates and deforms under shearforce. The resistance of the structure changes as a result of suchelongation.

Shown in FIG. 18 is an alternative shear force sensor, where frictionalforce may be measured by allowing relative movement between two rigidbodies.

FIG. 19A shows an example of a device where a base and a cover areseparated by an elastomeric layer that deforms as the cover moves acrossa surface. In this case, a measurement is obtained for the entire deviceindicating the total frictional force experienced.

FIG. 19B shows a plan view of a device having a lower surface consistingof concentric rigid bodies that are separated from a base by anelastomeric material. The rigid bodies are physically separated fromeach other by small gaps so that they can move separately with respectto a base. Electrodes attached to the elastomeric material connectingthe rigid bodies may be used to obtain separate resistance measurementsto indicate the amount of frictional force experienced by differentrigid bodies.

FIG. 20 illustrates how a wafer may move with respect to a pad in oneembodiment. The pad is preferably a circular pad that rotates clockwise.The wafer rotates counter-clockwise and is moved laterally across thepad.

FIG. 21A shows a device that measures shear force at different radialand angular locations across a surface. FIG. 21A shows the bottom(cover) side of a device similar to that of FIG. 19B but with separaterigid bodies (separate shear force sensors) for different angular zones.

FIG. 21B shows an alternative device for measuring shear force atdifferent locations on a surface. Cut-outs are formed in a cover forshear force sensors with room to allow some displacement.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Process Condition Measuring Devices (PCMDs) include instrumented wafersthat have physical dimensions the same, or close to, those of aproduction wafer and that include sensors and electronics to measure atleast one process condition. Various PCMDs are described in U.S. patentapplication Ser. Nos. 10/718,269, 10/837,359 and 11/381,992. PCMDs maybe wired or wireless. A wired PCMD sends data to an external unit overwires (or optical fibers). A wireless PCMD either stores data in amemory in the PCMD or may transmit the data to an external unit.Generally, wireless PCMDs are more suitable for studying processes wherea wafer is rotated such as CMP.

One way to measure pressure on a wafer surface is to form a cavitywithin the wafer, leaving a thin layer over the cavity that acts as adiaphragm and deflects under pressure. FIG. 2 shows an example of awafer 211 having a cavity 213 that is covered by a diaphragm 215. Underpressure, the diaphragm 215 deflects by an amount 6 that depends on theexternal pressure. In general, 6 may be used as an indicator of pressureapplied to the lower surface of the wafer 211. Where a suitable sensoris used to sense deflection, and electronics are provided in the wafer211 to store sensor data or transmit sensor data (or store and latertransmit data), such a PCMD may provide actual pressure data during aprocess such as CMP. Pressure on the lower surface of a substrate duringCMP is generally less than five pounds per square inch (5 psi), inaddition to atmospheric pressure. In some cases, pressures may be up to15 psi, or even greater.

Various methods may be used to measure the deflection of a diaphragmsuch as diaphragm 215 of FIG. 2. One convenient method is to form afirst capacitor electrode on the diaphragm, another electrodecapacitively coupled to the first capacitor electrode fixed within thecavity and measure any change in capacitance. A second convenient methodis to use a strain gauge. In general, it is preferable that thedeflection in a diaphragm used in this application should be small sothat the surface being eroded behaves similarly to that of a productionwafer that does not contain cavities and does not deflect in this way.Generally, such a deflection is maintained at less than 10 microns,though in some cases deflections may exceed 10 microns. This may beachieved by choosing appropriate dimensions and material of theappropriate flexibility for the diaphragm and wafer of FIG. 2.

FIGS. 3A-3D show different embodiments where capacitance is used tomeasure deflection. These capacitive pressure sensors use a cavityformed in a laminated wafer. A laminated wafer or other sturcture isformed to include a base and a cover, the base generally being thickerthan the cover. The cover, or a portion of the cover, is sufficientlythin so that it deflects under pressure. The base is generally formed bythinning a Silicon wafer and the cover is generally formed by thinning aSilicon wafer that has been processed up to a point where it is to besubjected to CMP processing. In this way, the lower surface of the coverclosely resembles the lower surface of a production wafer including thesame materials and topology. The base and cover are attached to form asingle unit. In general, the thickness of the unit (PCMD) formed is suchthat the pressures at the lower surface of the unit are close to thoseof a production wafer. This may require a thickness that is close to thethickness of a production wafer because a thicker PCMD would generallybe stiffer and thus distribute pressure differently. Preferably, thesecapacitive pressure sensors simulate a real work piece or substrate thatis undergoing a CMP process or a substrate to which a CMP head is to beapplied (where the CMP head needs to be tuned). For this purpose, it ispreferable for the laminated wafer or structure to have properties (suchas one or more of the following: dimensions, hardness, area andflexibility) that are substantially the same as those of a realsubstrate, such as a semiconductor wafer or flat panel display panel.

FIG. 3A shows a cross section of a first capacitive pressure sensorwhere a cavity 321 is formed in a separation layer 323 that extendsbetween a base 325 and a cover 327. The separation layer 323 may beformed of a material such as Kapton® polyimide film that may be havecut-outs formed according to a predetermined pattern. An electricalinsulator 329 a is formed on the cover 327 and a capacitor electrode 331a is formed on the insulator 329 a. In one example, the insulator isbetween 5 microns and 50 microns thick. The electrode 331 a may beformed by attaching a metal foil or by depositing a metal layer. Aninsulator 329 b and electrode 331 b are similarly formed on the base325. The base 325, cover 327 and separation layer 323 are aligned duringassembly so that the electrodes 331 a, 331 b are in cavity 321. In thisembodiment, no special topology is formed in opposing surfaces of eitherthe base 325 or the cover 327. These surfaces of the base 325 and thecover 327 may be planar.

FIG. 3B shows an alternative embodiment where a cavity 333 is formedinto a base 335. The cavity 333 may be machined, etched or otherwiseformed in the base 335. An insulator 337 a is then formed in the cavity333 and an electrode 339 a is formed on the insulator 337 a as before.An electrode 339 b and insulator 337 b are similarly formed on the cover341.

FIG. 3C shows an alternative embodiment where a cavity 343 is formedinto a cover 345. Insulators 347 a, 347 b and electrodes 349 a, 349 bare formed as before. The cover 345 may be relatively thick in thisexample because it is reduced to a suitable thickness where cavities areformed. The examples of FIGS. 3A-3C show three locations for the cavity:in a separation layer, in a base, and in a cover. A cavity may also beformed in a combination of these components, for example partially inthe base and partially in the cover, or partially in a separation layerand partially elsewhere, either in the base or in the cover or in both.

It should be noted that the drawings are not to scale and are notintended to accurately represent the relative proportions of thefeatures shown. Certain dimensions are exaggerated to more clearly showthe structures. In one example, a capacitive sensor includes a cavityhaving a diameter of 10 millimeters and an electrode of between 3 and 10millimeters diameter, with a spacing between electrodes of 25-50microns. The diaphragm may have a thickness between 125 microns and 800microns. The insulators in this example have a thickness of 25 micronsand the electrodes have a thickness of less than 25 microns. In otherexamples, different dimensions may be used. Such a capacitive sensor maybe able to resolve pressure to an accuracy of 0.01 pounds per squareinch.

FIG. 3D shows another embodiment where instead of forming localinsulators to isolate capacitor electrodes from the underlying surface,blanket insulating layers 351 a, 351 b are formed on both a base 353 andon a cover 355 respectively. A blanket layer extends over all exposedsurfaces on at least one side of a wafer. The blanket layer is formed insuch a way that the wafer is not warped and thus retains a substantiallyplanar surface. Such an insulating layer may be formed by deposition ormay be grown, such as by growing a Silicon Dioxide layer on a Siliconsurface. Where a cavity is formed in either the cover or the base, theinsulating layer may be formed after the cavity is formed so that theinsulating layer extends across surfaces of the cavity. A blanketinsulating layer may be used as an alternative to individual insulatorsin any of the above examples.

The base and cover may be electrically isolated from each other in somecases or may be electrically connected as described in U.S. patentapplication Ser. No. 11/381,992. The base and cover may be formed ofeither doped or undoped material and so may have different electricalconductivities according to requirements. Where the base and cover areundoped or have little doping so that the resistivity of the base andcover material is high, it may be possible to place electrodes directlyon the surface of the base or cover (without an insulator: or insulatinglayer). Where either the base or the cover is conductive, a parasiticcapacitor may be formed between the conductive base (or cover) and anelectrode that is separated from it by an insulator. In order to reducethe effects of such a parasitic capacitor, dimensions may be chosen sothat the capacitive sensor has a greater capacitance than the parasiticcapacitor.

FIG. 4A shows a plan view of a base 459 formed from a bare Siliconwafer. The base contains a number of cavities, including cavity 461.Within these cavities insulators, such as insulator 463, are formed.Capacitive sensor electrodes, such as electrode 465, are formed on theinsulators. Thus, the base 459 of FIG. 4A corresponds to the base 335shown in FIG. 3B. FIG. 4A also shows interconnects (pads), includinginterconnect 467 that form connections between the top capacitive sensorelectrodes and the electronics in the base. Both electrodes areconnected to electronic circuits (not shown) in the base to allow thecapacitance to be measured. The cavities and electrodes of this exampleare circular in shape, in other examples square, rectangular or othershaped cavities and electrodes may be used. The shapes of the electrodeor electrodes are not necessarily the same as the shapes of the cavitiesin which they are located. FIG. 4A shows sensor cavities extending alonga diameter of the base. It may generally be assumed that the pressuredistribution in a CMP process is radially symmetric (having the samepressure at all points along a given radius). However, in some casessensor cavities may be distributed in a different manner so thatpressures at are obtained at different angular locations.

FIG. 4B shows a plan view of a cover 469 formed from a thinned bareSilicon wafer. Cover 469 is designed to be attached to the base 459 ofFIG. 4A to form an instrumented wafer that includes a number ofcapacitive pressure sensors. Insulators, such as insulator 471, areformed on the cover 469 and capacitive sensor electrodes, such aselectrode 473, are formed on the insulators. Also shown areinterconnects to the base, including interconnect 475. Theseinterconnects are aligned with interconnects on the base to form anelectrical connection between electrodes and the electronics.

FIG. 5A shows a plan view of a base 577 of a PCMD according to anotherembodiment. In the example of FIG. 5A, no separate insulators areprovided on the base 577 because the base 577 is formed from a Siliconwafer with an insulating layer (as shown in FIG. 3D). Capacitive sensorelectrodes, including electrode 579, are placed directly on theinsulating layer. Cavities, such as cavity 581, may either be formed inthe base 577 or may be formed in a spacer layer that has holes locatedbetween electrodes of the base and cover. In general, some electroniccircuits (not shown) are also located in or on such a base and suchelectronic circuits are connected to the electrodes on the base and theelectrodes on the cover.

FIG. 5B shows a plan view of a cover 583 designed to be attached to thebase 577 of FIG. 5A to form a PCMD (instrumented wafer). Cover 583 hasan insulating layer formed of Silicon dioxide or other suitabledielectric material and so does not require separate insulators underindividual electrodes. Electrodes, such as electrode 585, are formed (bydeposition or otherwise) directly on the insulating layer. FIG. 5B alsoshows interconnects, including interconnect 587 that connect theelectrode of the cover to electronics in the base 577. A groove (ortrench) 579 is provided to allow connection between the electrode 585and the interconnect 587. An electrical connection between theinterconnect and the electrode may be formed by the same deposition stepthat forms the electrode 585 or may be formed separately. In oneexample, electrodes and interconnects are formed by silk screening orsimilar thick film techniques.

In general, where a cavity is formed for a pressure sensor, it isdesirable to isolate the cavity from the exterior environment. Thisprevents foreign material from entering the cavity, which could affectsensor performance. In particular, slurry used in CMP could cause damageto electrodes and other components if it entered such a cavity. However,an isolated cavity may experience a significant increase in pressure asa diaphragm is deflected. Even though the change in the volume of thecavity is small, if the cavity itself is small, the change in volume andhence the change in pressure may be significant. Such a pressure changeis generally undesirable because it may cause a non-linear relationshipbetween deflection and the external pressure.

One way to reduce the pressure change caused by a diaphragm deflectinginto a cavity is to provide an additional volume in communication withthe cavity. This additional volume reduces the effect of volume changecaused by diaphragm deflection on pressure in the sensor cavity. Theadditional volume may be considered a reservoir. Such a reservoir isgenerally formed so that its volume does not change as a result ofexternal pressure. For example, support may be provided to ensure thatsignificant deflection does not occur in a reservoir.

FIG. 6A shows a first example of a wafer 689 having sensor cavities withreservoirs. For example, sensor cavity 691 connects with reservoir 693.A reservoir may be formed as a cavity in the base (or cover, orseparation layer, or a combination of these components) in the samemanner as the cavity for the sensor. A channel 695 connects thereservoir 693 to the sensor cavity 691. To avoid significant volumechange in a reservoir, supporting structures 697 extend across areservoir to limit any deflection that might occur in the cover overthis area. Each sensor cavity of FIG. 6A has a dedicated reservoir. Insome cases, a reservoir may be deeper than a sensor cavity so that itsvolume is greater for a given cross sectional area.

FIG. 6B shows an alternative configuration to that of FIG. 6A. In FIG.6B, instead of dedicated reservoirs, sensor cavities 699 a-i share areservoir system that interconnects cavities 699 a-i and reservoirs 602a, 602 b. Such a reservoir system may be formed by the same process usedto form sensor cavities 699 a-i. A pattern of sensor cavities,reservoirs and interconnecting channels may be formed in the base(and/or other components) as shown. In this example, the reservoirsystem is isolated from the exterior of the PCMD so that no foreignmatter can enter the reservoir system and the pressure in the reservoirsystem remains stable.

In some cases it may be desirable to have an opening from a reservoirsystem in a PCMD to the exterior of the wafer. For example, it may bedesirable to equalize the pressure in the reservoir system with theambient pressure. In some cases, equalization may be used to eliminate apressure differential that might be caused by different atmosphericpressure resulting from use at different altitudes or in differentweather conditions. It may also be desirable to bring the reservoirsystem to a predetermined condition before use. For example, thereservoir system may be brought to a desired pressure, either aboveatmospheric pressure or below atmospheric pressure (under vacuum). Thereservoir system may also be filled with a particular gas or mixture ofgases if desired.

FIG. 7 shows an example of a PCMD 704 with a reservoir system that hasan opening 706 to the exterior of PCMD 704. A valve is provided toselectively connect the opening 706 to the reservoir system.Microelectromechanical Systems (MEMS) technology enables valves andother components to be formed on an extremely small scale. A MEMS valve708 may be formed in the base, or may be formed separately and attachedto the base. The MEMS valve may be controlled by electronic circuits inPCMD 704. When PCMD 704 is in use, the MEMS valve will generally remainclosed to prevent foreign matter entering the reservoir system. The MEMSvalve 708 may be opened by an electronic circuit in PCMD 704, generallyin response to a signal provided from outside PCMD 704. This may occurduring a calibration or initialization procedure. An alternative to aMEMS valve is to provide a temporary blockage that covers the opening706. A suitable material, for example a polymer such as Silicone, may beused to block the opening. The blockage formed may be removed toconfigure the reservoir system.

In general, electronic circuits are provided in a PCMD to store datafrom the sensors. Circuits may alternatively transmit data to a receiveroutside the PCMD. In some cases, data is first stored and thentransmitted. Such circuits may be formed and connected in a number ofways. In one arrangement, electronic circuits include one or moreintegrated circuits that are placed in cavities in a base (or cover).The integrated circuits are bonded in place. Electrical connectionsbetween integrated circuits and sensors are provided by conductivetraces formed on the surface of the base (or cover). Connection pads onthe integrated circuits may be bonded to these traces. Integratedcircuits used in this configuration may be used in the form ofsemiconductor dies so that they have small profiles and small thermalcapacities. Instead of using traces on a surface, insulated wires mayextend between components including sensors and integrated circuits.Such wires may be bonded to the components and may run through trenchesformed within a PCMD.

In another arrangement, electronic circuits and connections betweencircuits are formed as a flex circuit assembly that is attached to abase. Generally, cavities and grooves are formed in the base so thatsuch a flex circuit presents a surface that is flush with the surface ofthe base. A cover may then be attached. Descriptions of the use of suchflex circuits and traces in PCMDs are provided in U.S. patentapplication Ser. Nos. 10/837,359 and 11/381,992.

An example of a PCMD 810 that includes a flex circuit 812 is provided inFIG. 8A. The flex circuit 812 includes at least one microprocessor 814that is in communication with the sensors. Microprocessor 814 mayinclude a memory for storing data from the sensors, and/or transmittercircuits for transmitting such data to an external device, preferably bywireless transmission, such as radio waves. In addition, the flexcircuit 812 provides power connections between the battery 816, orbatteries, and other components. In addition to capacitive sensors 818a-i, FIG. 8A shows temperature sensors T1, T2 and T3. Sensors T1, T2, T3are located close to capacitive pressure sensors 818 a-c so that anindividual temperature sensor may provide temperature for a specificcapacitive sensor. In some examples a temperature sensor is provided foreach pressure sensor 818 a-i. In this way, the temperature for aparticular capacitive sensor may be used to compensate for anytemperature variation that might affect the physical or electricalbehavior of the capacitive sensor. Temperature sensors T1, T2, T3 may beformed as part of the flex circuit 812 or may be separately formed andattached to the flex circuit 812.

FIG. 8B is a side view of a member such as a plate with a base 824 and acover 822 enclosing a cavity housing 826 a pair of capacitively coupledelectrodes 826 a and 826 b not connected to the cover to sense aparasitic capacitance in the plate to illustrate another embodiment ofthe invention. Electrodes 826 a and 826 b are separated by a dielectriclayer 828. FIG. 8C is a top plan view of two pairs 826 and 836 ofcapacitively coupled electrodes adjacent to one another, one pair (826)not connected to the cover to sense a parasitic capacitance in theplate, and the other pair (836) connected (not shown in FIG. 8B) to thecover to sense a deflection of the cover. The capacitance of pair 826 isan indication of the parasitic capacitance experienced by pair 836.Thus, the capacitance of pair 826 may be used to adjust the measurementof the deflection of cover 822 by pair 836, so as to reduce the effectof the parasitic capacitance experienced by pair 836 on the measurement.This may be performed by microprocessor 814 in FIG. 8A, after themicroprocessor 814 receives data related to the capacitances of pairs826 and 836 through flex circuit 812 in FIG. 8A, and the change incapacitance of pair 836 caused by deflection of the cover 822.

Where electrodes are formed on the base and cover, these electrodes areconnected to the flex circuit so that electronic circuits within theflex circuit can detect any capacitance change. Similarly, temperatureor other sensors that are not formed integrally with the flex circuitare connected to the flex circuit. FIG. 9 shows an example where anelectrode 920 on a cover 922 is connected to a pad 924 on a flex circuit926. The electrode 920 is connected to an interconnect 928 that isoutside the sensor cavity 930 (as shown in FIG. 5B). The interconnect928 is isolated from the cover 922 by an insulating layer 932A on thecover 922. Pad 924 on the flex circuit 926 overlies the interconnect 928and this pad is electrically connected to one or more integratedcircuits in the flex circuit 926. The interconnect 928 is attached tothe pad 924 by an electrically conductive epoxy 934. A similarconnection (not shown) may be made to the base electrode 936. Similarconnections may be formed for temperature sensors. Flex circuit 926 liesin trench 938 in this example. Thus, the electronics is partially in thecavity (the electrodes 920 and 936), and partially (flex circuit 926) inthe trench 938 which can serve also as a reservoir to reduce the effectof deflection of the cover on the pressure measurement.

FIG. 10 shows another embodiment where a capacitive sensor is formedintegrally with a flex circuit 1042. The flex circuit includes twoelectrodes 1044 a, 1044 b that are separated by a dielectric layer 1046to form a capacitor 1040. The dielectric layer 1046 may be formed of asuitably compressible elastomeric material. The portion of the flexcircuit 1042 that contains the capacitor is bonded to both the base 1048and the cover 1050 using thin layers 1052 a, 1052 b of adhesive. Flexcircuit 1042 lies in trench 1056.

In the examples of both FIGS. 9 and 10, trenches are provided for theflex circuits 926, 1042. Trenches 938, 1056 connect to the sensorcavities 930, 1054 respectively. Generally, a flex circuit does notfully occupy the flex circuit trench so that some unoccupied volumeremains around the flex circuit. This extra volume allows for some gasflow through the trenches formed for the flex circuit. Also, someunoccupied volume generally remains around some integrated circuits ofthe flex circuit. Thus, the unoccupied volumes within the trenches andcavities formed for the flex circuit may form a reservoir system thatreduces pressure variation within sensor cavities. A controlled openingfrom such a reservoir system to the exterior of the PCMD may be providedas previously described.

In one example, a flex circuit includes one or more capacitive sensors,or is attached to one or more capacitive sensors, and also includeselectrical connections from the one or more sensors to an integratedcircuit that provides an output that is dependent on the capacitance ofthe capacitive sensor. An example of an integrated circuit that may beused is an Analog Devices AD7746 capacitance to digital converter. Thisintegrated circuit provides an output that may then be sent to amicroprocessor for storage or transmission. In an alternativeembodiment, capacitors connect directly to a microprocessor thatperforms a capacitance to digital conversion internally.

An alternative to using a capacitive sensor to measure pressure is touse a strain gauge. A sensor cavity may be formed according to any ofthe examples described above so that a diaphragm is formed that willdeflect under pressure. Instead of placing capacitor electrodes oneither side of this cavity, a strain gauge is placed so that it will bedeflected as the diaphragm is deflected.

FIG. 11 shows a first example where a sensor cavity 1158 is formedwithin a base 1160 (note that this drawing shows the cover 1162 abovethe base 1160, the opposite orientation to that of previous drawings andthe opposite to the orientation during CMP). Spacers 1164 a, 1164 b areplaced under a strain gauge 1166 so that the strain gauge 1166 candeflect downwards. A deflection augmenting element 1168 (such as a smallbead, tube, corrugated structure or some other small rigid body) isplaced between the upper surface of the strain gauge 1166 and the cover1162. Thus, any deflection in the cover 1162 will cause the strain gauge1166 to deflect. The deflection augmenting element 1168 causes a greaterdeflection in strain gauge 1166 than the deflection in cover 1162, thusaugmenting the measurement obtained, which may increase resolution. Inone example, a deflection augmenting element is machined into either acover or a base. The strain gauge 1166 may be connected to electroniccircuits in the base 1160 as previously described.

FIG. 12A shows an alternative arrangement where a strain gauge 1272 isbonded to a cover 1274 so that the strain gauge 1272 deflects along withthe cover 1274. A suitable strain gauge may be a resistive strain gauge,a piezoresistive strain gauge, a piezoelectric strain gauge or asemiconductor strain gauge such as a bar gauge.

FIG. 12B shows an alternative embodiment to that of FIG. 12A. Here acavity 1276 is formed in cover 1278 and a strain gauge 1280 is formed oncover 1278. Base 1282 may be planar in this example.

FIG. 13 shows an embodiment where pressure sensors 1384 a-d are placedbetween a wafer 1386 and a CMP head 1388. A production wafer may be usedfor wafer 1386 or a PCMD may be used instead. Pressure sensors may becapacitive sensors formed from two metal electrodes separated by acompressible dielectric. In one example, sensors 1384 a-d are attachedto wafer 1386. In another example, sensors 1384 a-d are attached to theCMP head. In either case, sensors 1384 a-d measure the pressure betweenthe CMP head 1388 and wafer 1386 at various points on the wafer surface.Sensors 1384 a-d are connected to electronics module 1389, which ismounted to CMP head 1388. Electronics module 1389 may store data fromsensors 1384 a-d, or may transmit the data in real time to another unit.For example, electronics module 1389 may include a Bluetooth or otherwireless communication device to allow real time transmission of data.

In some cases, it may be desirable to calibrate a pressure measurementwafer (PCMD), either initially as part of a factory calibration or inthe field. In some cases, the pressure readings from pressure sensorsmay change with use. For example, as a PCMD is subject to CMP, thethickness of a diaphragm is reduced, thus affecting pressuremeasurements based on the deflection of the diaphragm. One option is tocoat a surface with a hard layer (for example, Silicon Nitride) toreduce erosion. However, such hard layer may have differentcharacteristics to materials of production wafers. Another option is todeposit additional material periodically to replace material removed byCMP. This may be done at relatively low temperatures for some materials(e.g. Copper) but may require high temperatures for other materials(e.g. Silicon).

FIG. 14 shows a pressure calibration apparatus that may be used tocalibrate a pressure sensing PCMD as previously described. A PCMD 1490is placed on a first surface 1492 with pressure sensors facing up. Asecond surface 1494 is located at a fixed distance above first surface1492 and an inflatable bladder 1496 is placed between the PCMD 1490 andsecond surface 1494. Inflatable bladder 1496 is inflated to apredetermined pressure (or to a series of predetermined pressures)through pressure regulator 1498. Sensor readings may be recorded foreach sensor at each predetermined pressure applied, and this data may beused to calibrate the sensor readings. A PCMD may be periodicallycalibrated in this manner to correct for removed material or othereffects. Preferably, the pressure sensors are heated or cooled topredetermined temperatures by means of a temperature control instrument1450.

Generally, a PCMD according to certain examples described above is usedby placing it, with the cover side down, in a CMP processing system. ThePCMD undergoes the same process that a production wafer goes through.During the process, the PCMD measures pressure at different locationsacross the lower surface. The data generated from such measurements isstored in a memory. After processing, the data is downloaded andanalyzed to provide information about pressure across the PCMD as afunction of time. Temperature data may be separately recorded.Temperature data may also be used to compensate pressure sensor readingfor any temperature effects.

Various examples refer to CMP applications for a pressure sensing waferor PCMD. However, such a pressure sensing wafer may be used in variousother processes including processes that take place at pressures greateror less than atmospheric pressure. One example of a process that may bestudied using a pressure sensing wafer is an immersion photolithographyprocess, where pressure caused by an air knife (used to contain a waterpuddle) may be measured. Another process is CMP scrubbing or cleaning, aprocess that cleans a wafer after CMP. The pressure applied to the waferduring such a clean process may affect the cleanliness of the wafer.Certain processes hold a wafer to a chuck by electrostatic force. Theforce that such an electrostatic chuck (ESC) applies may vary over timeand may be adjusted to prevent wafers from moving during processing. Apressure measuring PCMD may be used to measure the pressure between awafer and such a chuck to determine the appropriate adjustment (if any).Substrates other than Silicon wafers may be instrumented to form a PCMD.For example, GaAs wafers or Flat Panel Display (FPD) substrates may besimilarly provided with cavity based sensors.

In one embodiment, a PCMD has the same diameter as a 200 millimeter or300 millimeter wafer and the same (or similar thickness). The PCMDincludes at least one cavity that has a sensor to detect deflection intothe cavity caused by external pressure. The PCMD may further include atleast one temperature sensor. The PCMD may also include a flex circuitwith at least one integrated circuit and conductors between theintegrated circuit and sensors. The PCMD may also include at least onebattery. A sensor to detect deflection in a cavity may be capacitancebased or strain gauge based. A cavity may be connected to a dedicatedreservoir or to a shared reservoir. A reservoir may be provided with anexternal opening.

In general, removal of material in CMP is caused by two mechanisms:mechanical action and chemical action. Although these mechanisms areclosely linked, it may be desirable to try to separately measureparameters associated with each. One measurement that may be ofparticular value in measuring mechanical action is the frictional forcebetween a wafer and a pad as the wafer moves with respect to the pad.Generally, mechanical abrasion of material increases with increasingfrictional force. Frictional force may be used to provide a shear forcein a structure that deforms in a manner that indicates the magnitude ofthe shear force. In general, greater frictional force provides greatermechanical action in removing material during CMP.

FIG. 15 shows a CMP head 1501 and an attached wafer 1503 moving withvelocity V with respect to a pad 1505. A layer of slurry 1507 extendsacross pad 1505. As wafer 1503 moves horizontally, it is pressed intopad 1505 so that there is some pressure between wafer 1503 and pad 1505.As wafer 1503 moves to the right in FIG. 15, it experiences a frictionalforce opposing its motion, indicated by force F. Frictional force Fgenerally depends on the coefficient of friction and also the normalforce (pressure) between wafer 1503 and pad 1505. However, as discussedabove, pressure is not always uniform across a wafer surface during CMP.Also, the velocity of relative motion between a wafer and a pad is notalways constant across a wafer. A wafer may be rotated, resulting in ahigher velocity for outer portions of the wafer than for inner portions.Also, the pad may rotate or otherwise move in a manner that does notprovide uniform velocity across a wafer surface. It may be useful tomeasure frictional force at different locations across a wafer surfaceduring CMP in order to estimate mechanical abrasion.

FIGS. 16A and 16B illustrate the effect of shear force on a structure1609 that is designed to deform under shear stress. FIG. 16A shows afirst rigid body 1611 in contact with a surface 1613. First rigid body1611 is connected to second rigid body 1615 by a portion of elastomericmaterial 1617. FIG. 16A shows structure 1609 at rest with respect tosurface 1613. FIG. 16B shows structure 1609 in motion, having velocityV, with respect to surface 1613. Structure 1609 is moved by applying aforce through second rigid body 1615. As a result of relative motionbetween first rigid body 1611 and surface 1613, a frictional force F iscreated. Frictional force F acts as a shear force causing portion ofelastomeric material 1617 to deform. For example, elastomeric material1617 may comprise a silicone elastomer with conductive elementsdispersed therein, such as small flakes, platelets, fibers or nanotubes.In this case, the deformation causes an offset of d between first rigidbody 1611 and second rigid body 1615 compared with their unloadedpositions. The magnitude of d is a function of F. A shear force sensormay be formed from two rigid bodies that have a limited range ofrelative displacement under shear force and have some mechanism formeasuring displacement. Preferably structure or member 1609 simulates areal work piece or substrate that is undergoing a CMP process. For thispurpose, it is preferable for its surface in contact with surface 1613to have a coefficient of friction that is substantially the same as thatof a real substrate, such as a semiconductor wafer or flat panel displaypanel. It is preferable for the structure 1609 to have dimensions thatare substantially the same as those of a real substrate. The shear forceis applied in a direction so that the force has at least one componentthat is perpendicular to the surfaces of structure 1609 and surface1613.

In one example, shown in FIG. 17A, a shear force sensor 1718 measuresdeformation due to shear force on an elastomeric material throughchanges in the electrical properties of the elastomeric material as itis deformed. In particular, the electrical resistance of such anelastomeric material may change as the material is deformed. Electrodesmay be provided to detect changes in the resistance of such anelastomeric material. FIG. 17A shows an example where electrodes 1719 a,1719 b are embedded in an elastomeric layer 1720 and an electricalresistance measuring unit 1721 measures an electrical resistance (alsoreferred to herein as simply “resistance”, the two terms usedinterchangeably herein) between them. Some elastomeric materials may beformed with anisotropic electrical characteristics. A suitableelastomeric material with anisotropic electrical characteristics maycomprise a silicone elastomer with conductive elements dispersedtherein, such as small flakes, platelets, fibers or nanotubes. Forexample, such materials may be electrically conductive in one directionand nonconductive in another direction. Such materials may be formed sothat a resistance changes with a deformation caused by shear(horizontal) force but is not significantly affected by a compressive(vertical) force. Electrodes for resistance measurement may be formed inthe elastomeric material or on one or both surfaces on either side, forexample as patterns of interdigitated fingers.

FIG. 17B shows an alternative shear force sensor 1799 where resistanceis measured by an electrical resistance measuring unit (not shown), suchas unit 1721 of FIG. 17A, between electrodes 1797 a, 1797 b, which areconnected by a structure 1795 that varies in resistance as a result ofshear induced deformation. In particular, structure 1795 is arranged sothat it runs diagonally through elastomeric layer 1793. Thus, structure1795 elongates as elastomeric layer 1793 deforms under shear force. Theresistance of structure 1795 changes as a result of such elongation.Structure 1795 may be formed of metallic platelets (e.g. Aluminum),carbon fibers, carbon black particles or similar small conductive bodiesthat form a conductive pathway. As the conductive pathway is stretched,conduction diminishes because of poor contact between conductive bodies.Structure 1795 is generally not sensitive to downward pressure.

In an alternative shear force sensor 1822, shown in FIG. 18, frictionalforce may be measured by allowing relative movement between two rigidbodies. A lower rigid body 1823 includes a protrusion 1825 that extendsinto a cavity 1827 in an upper rigid body 1829. The location ofprotrusion 1825 within cavity 1827 is established by springs or someother mechanism that allows some lateral movement when force is applied(e.g. elastomeric material). As lower rigid body 1823 moves across asurface 1831, a frictional force F is generated that tends to causelower rigid body 1823 to move with respect to upper rigid body 1829.Such a relative movement may be observed as a change in distances d1, d2between protrusion 1825 and walls of cavity 1827. Distances d1 and d2may be measured by any suitable technique including capacitively orusing piezoelectric material. Shear force may occur in any lateraldirection, so a shear force sensor may detect displacement from a staticcondition in more than one direction. For example, shear force sensor1822 may also measure distances perpendicular the cross section shown.Thus, both the magnitude and direction of shear force may be measured.FIG. 18 shows upper rigid body 1829 in contact with surface 1831. Inother examples, such an upper rigid body may not have any contact with asurface and only the lower rigid body is in contact. Upper rigid body1829 may be a base of a PCMD that includes electronic components thatreceive data from shear force sensor 1822.

A PCMD may measure frictional force using the structures describedabove. FIG. 19A shows a first example of a PCMD 1936 where a base 1933and a cover 1935 are separated by an elastomeric layer 1937 that deformsas cover 1935 moves across a surface. In this case, a measurement isobtained for the entire PCMD 1936 indicating the total frictional forceexperienced. However, in some cases, it is desirable to obtain valuesfor frictional force at different points on a wafer, or PCMD.

FIG. 19B shows a plan view of a PCMD 1938 having a lower surfaceconsisting of concentric rigid bodies 1939 a-d that are separated from abase (not shown) by an elastomeric material. Rigid bodies 1939 a-d arephysically separated from each other by small gaps so that rigid bodies1939 a-d can move separately with respect to a base. As PCMD 1938rotates, frictional force is different for different rigid bodies 1939a-d. Electrodes attached to the elastomeric material connecting rigidbodies 1939 a-d may be used to obtain separate resistance measurementsto indicate the amount of frictional force experienced by differentrigid bodies. In this way, instead of a single measurement of frictionalforce experienced by a PCMD, four different measurements are obtained,representing shear force experienced by four concentric zones of awafer. Thus, PCMD 1938 may be considered to have four concentric shearforce sensors.

In some cases, it may be desirable to obtain shear force measurementsfor zones having different angular displacements as well as differentradial displacements. FIG. 20 illustrates how a wafer 2041 may move withrespect to a pad 2043. Pad 2043 is a circular pad that rotates clockwisein this example by an instrument 2050, such as a motor in a conventionalmanner. Wafer 2041 rotates counter-clockwise and is moved laterallyacross pad 2043 by an instrument 2052 such as a motor and a gearmechanism in a conventional manner, which instrument may be one and thesame as instrument 2050. The result of these different movements is thatthe speed with which a point on the wafer surface moves with respect tothe pad beneath it changes as the wafer rotates. For example, as shownin FIG. 20 the right side of wafer 2041 experiences a higher speed withrespect to the underlying portion of pad 2043 than the left side ofwafer 2041. Thus, shear force for a particular location on the wafersurface may oscillate from low to high. Also, the shear force changes aswafer 2041 moves laterally across pad 2043. By measuring localized shearforces, additional information may be obtained, such as maximum andminimum shear forces and patterns in changing shear force.

FIG. 21A shows a PCMD 2147 that measures shear force at different radialand angular locations across a surface. FIG. 21A shows the bottom(cover) side of a PCMD 2147 similar to PCMD 1938 but with separate rigidbodies (separate shear force sensors) for different angular zones. Thus,instead of measuring average frictional force for different radialzones, PCMD 2147 measures frictional force for four different portionsof each radial zone. This may provide maximum and minimum shear forceinformation that may be useful.

FIG. 21B shows an alternative PCMD 2149 for measuring shear force atdifferent locations on a surface. Whereas in earlier figures the shearforce sensors on the lower surface of a PCMD occupied the entire lowersurface (or nearly the entire lower surface), here shear force sensors2151 a-i occupy only a portion of the lower surface of PCMD 2149.Cut-outs are formed in a cover for shear force sensors 2151 a-i withroom to allow some displacement. PCMDs 1936, 1938, 2047 and 2149 maymeasure shear force using a shear force sensor such as sensors 1718 or1799 that use elastomeric material, or a shear force sensor such assensor 1822 that uses displacement, or using any other suitable shearforce sensor. In general, one or more shear force sensors may becombined with other sensors in a PCMD. In particular, it may bedesirable to include pressure sensors to measure compressive force,temperature sensors and material removal rate sensors for CMPapplications. A microprocessor (not shown) similar to microprocessor 814in FIG. 8A may be used to receive the data from the shear force sensorssuch as sensors 1718 and 1799, and data from other sensors through flexcircuits of the type described above. Preferably such microprocessorincludes a memory for storing data from the sensors, and/or transmittercircuits for transmitting such data to an external device, preferably bywireless transmission, such as radio waves.

In some PCMDs, sensors may collect acoustic input that is used tocharacterize a CMP process. For example, as a surface is eroded, afrequency of wafer vibration may change. This change may be detected byone or more acoustic sensors in the wafer or in a CMP head and used toobtain information regarding the amount of material removed. Thus,certain acoustic sensors may be considered removal rate sensors.

All patents, patent applications, articles, books, specifications, otherpublications, documents and things referenced herein are herebyincorporated herein by this reference in their entirety for allpurposes. To the extent of any inconsistency or conflict in thedefinition or use of a term between any of the incorporatedpublications, documents or things and the text of the present document,the definition or use of the term in the present document shall prevail.

Although the various aspects of the present invention have beendescribed with respect to certain preferred embodiments, it isunderstood that the invention is entitled to protection within the fullscope of the appended claims.

1. A process condition measuring device for measuring pressure or forceon a surface of a substrate undergoing a process, said devicecomprising: a semiconducting member having a property that issubstantially the same as a property of the substrate, said membercomprising a diaphragm; and sensor means physically connected to thediaphragm, wherein said sensor means is for measuring deflection of thediaphragm when the diaphragm is in contact with and pressed against asurface employed in said process, said sensor means comprising at leastone pair of capacitively coupled electrodes, wherein a capacitance ofthe at least one pair varies as a function of deflection of thediaphragm.
 2. The device of claim 1, wherein said diaphragm is of suchflexibility that deflection of said diaphragm is not more than about 10microns when the diaphragm is in contact with and pressed against thesurface employed in the process.
 3. The device of claim 1, said membercomprising a plate, wherein said property includes one or more of thefollowing: flexibility, area, hardness and physical dimensions of theplate.
 4. The device of claim 1, said member comprising a base and acover defining at least one cavity between the base and cover forhousing said sensor means, said cover comprising said diaphragm.
 5. Thedevice of claim 4, wherein said at least one cavity is formed on asurface of the base facing the cover, or on a surface of the coverfacing the base.
 6. The device of claim 4, said member furthercomprising a separation layer between the base and cover, said at leastone cavity being formed in said separation layer.
 7. The device of claim4, said member defines therein at least one reservoir in communicationwith said at least one cavity to reduce effect of deflection of thediaphragm on pressure within the at least one cavity.
 8. The device ofclaim 7, further comprising an opening through which the at least onereservoir communicates with an external environment, and a valvecontrolling such communication.
 9. The device of claim 4, furthercomprising an electronic circuit, wherein at least a portion of saidelectronic circuit is in said at least one cavity, the electroniccircuit comprising a memory or a wireless transmission component, theelectronic circuit receiving data from the sensor means and storing thedata in the memory or transmitting the data using the wirelesstransmission component.
 10. The device of claim 9, wherein said memberdefines therein at least one reservoir in communication with said atleast one cavity to reduce effect of deflection of the diaphragm onpressure within the at least one cavity, and at least a portion of saidelectronic circuit is located in said at least one reservoir.
 11. Thedevice of claim 4, said member comprising a semiconductor wafer that hasdimensions and thickness that are substantially the same as those of aproduction semiconductor wafer.
 12. The device of claim 1, said processbeing a polishing or planarization process, said diaphragm comprisingone or more of the following: a wear resistant coating to reduce erosionby said polishing or planarization process, and additional depositedmaterial to replace material eroded by said process.
 13. The device ofclaim 1, said member comprising a plate, said sensor means including aplurality of pairs of capacitively coupled electrodes distributed acrossthe area extent of said plate, said device further comprising aplurality of temperature sensors, wherein each of the temperaturesensors is located in proximity to a corresponding pair of capacitivelycoupled electrodes for measuring temperature of said corresponding pairof capacitively coupled electrodes, said temperature sensors providingoutputs.
 14. The device of claim 13, further comprising an electroniccircuit responsive to said sensor means and the outputs of thetemperature sensors for adjusting measurements of each of thecorresponding pairs of capacitively coupled electrodes using the outputof the temperature sensor located in proximity to each of thecorresponding pairs.
 15. The device of claim 1, further comprising atleast one reference pair of capacitively coupled electrodes that is notconnected to said diaphragm for sensing a parasitic capacitance in saidmember.
 16. The device of claim 15, further comprising an electroniccircuit responsive to an output of said reference pair of capacitivelycoupled electrodes for adjusting measurements of said sensor means toreduce effect of the parasitic capacitance on such measurements.
 17. Thedevice of claim 15, further comprising a plurality of reference pairs ofcapacitively coupled electrodes that are not connected to said diaphragmfor sensing a parasitic capacitance in said member, each of theplurality of reference pairs located in proximity to a correspondingpair of capacitively coupled electrodes for reducing effect of theparasitic capacitance on measurements by such corresponding pair. 18.The device of claim 1, said process being a polishing or planarizationprocess, and said member is suitable for undergoing said process tosimulate behavior of said substrate in the process.
 19. The device ofclaim 1, said process being a process for tuning a polishing orplanarization head.
 20. A method for measuring pressure or force on asurface of a substrate that is undergoing a process, said methodcomprising: providing a device having a plate with a property that issubstantially the same as a property of the substrate, said platecomprising a diaphragm and at least one pair of capacitively coupledelectrodes, said at least one pair having a capacitance; and sensingdeflection of the diaphragm when the diaphragm is in contact with andpressed against a polishing or planarization surface, said sensingcomprising detecting a change in the capacitance of the at least onepair of capacitively coupled electrodes.
 21. The method of claim 20,wherein said property includes one or more of the following:flexibility, area, hardness and physical dimensions of the plate,wherein said device comprises a memory or a wireless transmissioncomponent, said method further comprising storing data related to thechange in the capacitance of the at least one pair of capacitivelycoupled electrodes in the memory or transmitting the data using thewireless transmission component.
 22. The method of claim 20, furthercomprising measuring a parasitic capacitance in said plate and reducingeffect of the parasitic capacitance on said sensing.
 23. The method ofclaim 20, further comprising inflating an inflatable member topredetermined pressures, sensing deflection of the diaphragm caused byinflation of the member, and using heating elements to heat the plate topredetermined temperatures during the inflating and sensing.
 24. Themethod of claim 20, said process being a polishing or planarizationprocess, and said plate is suitable for undergoing said process tosimulate behavior of said substrate in the process.
 25. The methoddevice of claim 20, said process being a process for tuning a polishingor planarization head.